Early 2011 Atlantic Hurricane Season Forecasts

A continuation of the pattern of much above-average Atlantic hurricane activity we've seen since 1995 is on tap for 2011, according to the latest seasonal forecast issued April 6 by Dr. Phil Klotzbach and Dr. Bill Gray of Colorado State University (CSU). They are calling for 16 named storms, 9 hurricanes, and 5 intense hurricanes. An average season has 10 named storms, 6 hurricanes, and 2 intense hurricanes. The new forecast is nearly identical to their forecast made in December, which called for 17 named storms, 9 hurricanes, and 5 intense hurricanes. Only six seasons since 1851 have had as many as 17 named storms; 19 seasons have had 9 or more hurricanes. The 2011 forecast calls for a much above-average chance of a major hurricane hitting the U.S., both along the East Coast (48% chance, 31% chance is average) and the Gulf Coast (47% chance, 30% chance is average). The Caribbean is forecast to have a 61% chance of seeing at least one major hurricane (42% is average.) Five years with similar pre-season November atmospheric and oceanic conditions were selected as "analogue" years that the 2011 hurricane season may resemble: 2008, 1999, 1996, 1955, and 2006. The first four years listed all had neutral to La Niña SST's during hurricane season, while 2006 had El Niño SST's. The average activity for these years was 12.6 named storms, 7.8 hurricanes, and 4.8 major hurricanes.

This year, the forecasters have introduced a new statistical model for their April forecasts. There are four components in this model:

1. Average sea-level pressure in March around the Azores in the subtropical Atlantic.

2. The average of January through March sea-surface temperatures (SST's) in the tropical Atlantic off the coast of Africa.

3. Average sea-level pressure in February and March for the southern tropical Pacific ocean west of South America.

The first two components are loosely linked together. Statistical studies have shown that a weaker subtropical high near the Azores, combined with warmer SST's off the coast of Africa in March are associated with weak winds near the surface and aloft from August to October. This decrease in wind speeds reduces wind shear which can disrupt forming storms. These March conditions also are associated with warmer SST's in August to October, which is also favorable for more tropical storms. For this forecast, the first component is strongly favorable for increased hurricane activity, while the second component is weakly negative.

The last two components represent the changes in sea-surface temperature and sea-level pressure that are the El Niño-Southern Oscillation (ENSO). Briefly speaking, El Niño conditions (warm sea-surface temperatures) are not favorable for Atlantic hurricanes. For more info on ENSO and hurricanes, Jeff has this article.

Using the ECMWF model as guidance (see Figure 1), the CSU group believes that SST's in the tropical Pacific will be neutral (less than 0.5°C from normal). This would have a small negative effect on hurricane activity. However, the tropical Pacific sea-level pressure shows that the atmosphere looks like a La Niña event is still going on. This is strongly favorable for Atlantic hurricane activity in the CSU group's model.

Figure 1. Forecasts of El Niño conditions by 20 computer models, made in March 2011. The ECMWF forecast used by the CSU group is represented by the dark orange square. The forecasts for August-September-October (ASO) show that 5 models predict El Niño conditions, 7 predict neutral conditions, and 5 predict a weak to moderate La Niña. El Niño conditions are defined as occurring when sea surface temperatures in the Equatorial Pacific off the coast of South America ( the "Niño 3.4 region) rise to 0.5°C above average (top red line). La Niña conditions occur when SSTs in this region fall to 0.5°C below average. Image credit: Columbia University.

How accurate are the April forecasts? While the formulas used by CSU do well in making hindcasts--correctly modeling the behavior of past hurricane seasons--their April hurricane season forecasts have had no skill in predicting the future. This year's April forecast is using a new system and has not yet produced a verified forecast. The scheme used in the past three years successfully predicted active hurricane seasons for 2008 and 2010, but failed to properly predict the relatively quiet 2009 hurricane season. A different formula was used prior to 2008, and the April forecasts using that formula showed no skill over a simple forecast using climatology. CSU maintains an Excel spreadsheet of their forecast errors ( expressed as a mathematical correlation coefficient, where positive means a skilled forecast, and negative means they did worse than climatology) for their their April forecasts. For now, these April forecasts should simply be viewed as an interesting research effort that has the potential to make skillful forecasts. The next CSU forecast, due by June 1, is the one worth paying attention to. Their early June forecasts have shown considerable skill over the years.

Figure 2. Accuracy of long-range forecasts of Atlantic hurricane season activity performed by Phil Klotzbach and Bill Gray of Colorado State University (colored squares) and Tropical Storm Risk, Inc. (colored lines). The CSU team's April forecast skill is not plotted, but is less than zero. The skill is measured by the Mean Square Skill Score (MSSS), which looks at the error and squares it, then compares the percent improvement the forecast has over a climatological forecast of 10 named storms, 6 hurricanes, and 2 intense hurricanes. TS=Tropical Storms, H= Hurricanes, IH=Intense Hurricanes, ACE=Accumulated Cyclone Energy, NTC=Net Tropical Cyclone Activity. Image credit: TSR.

I remember when a very close friend explained us how he saved both his wife and himself holding a mattress over him after the whole house blew away... Those were the longest minutes and hours that they ever lived...

Luckily our house stayed intact. Some minor damage, but others were not so fortunate. I had full shutters around the entire house, and the previous year had a hurricane garage door installed. Not many people did. I still do believe it made the difference.

It is funny, but at the time, it was a terrible experience. We lived in Old Cutler at the time,(part Cutler Ridge, now called Cutler Bay.) Years later, we can laugh about it, a little.

I remember when a very close friend explained us how he saved both his wife and himself holding a mattress over him after the whole house blew away... Those were the longest minutes and hours that they ever lived...

ScienceDaily (Apr. 6, 2011) — In the past few weeks, exceptional weather conditions have led to unprecedented ozone depletion over the Arctic. Ground and satellite observations by researchers at the Laboratoire Atmosphères, Milieux, Observations Spatiales (CNRS/UVSQ/UPMC) as well as French models show that ozone loss reached around 40% at the end of March. The phenomenon was caused by an extremely cold and persistent stratospheric winter, resulting in significant ozone destruction, which, unusually, continued into spring.Link

ScienceDaily (Apr. 7, 2011)-Since the double disaster of the 9.0 magnitude earthquake and tsunami that affected hundreds of thousands of people and seriously damaged the Fukushima Daichi power plant in Japan on 11 March 2011, minute traces of radioactive emissions from Fukushima have spread across the entire Northern Hemisphere. A monitoring network designed to detect signs of nuclear explosions picked up these traces from the stricken power plant.

To date, more than 30 radionuclide stations that are part of the International Monitoring System (IMS) have provided information on the spread of radioactive particles and noble gases from the Fukushima accident. The IMS is a global network that will comprise 337 facilities when complete. Sixty-three of the 80 planned IMS radionuclide stations are already operational and able to detect airborne radioactivity.

Nine days after the accident, the radioactive cloud had crossed Northern America. Three days later when a station in Iceland picked up radioactive materials, it was clear that the cloud had reached Europe. By day 15, traces from the accident in Fukushima were detectable all across the northern hemisphere. The radioactive materials remain confined to the northern hemisphere as the equator acts as a dividing line between the northern and southern air masses.

Quoting sunlinepr:This is a montage of local television media coverage in Miami and from the Weather Channel on Hurricane Andrew which struck Homestead Florida on August 24th 1992. Andrew is only the 3rd cat.-5 Hurricane to ever make landfall anywhere in the United States since records have been kept. The storm produced sustained winds of 165-MPH with gusts of 220-MPH in parts of South Miami-Dade County.

""

Jim Cantore with hair. I thought I was the only one alive who remembers that.

This is a montage of local television media coverage in Miami and from the Weather Channel on Hurricane Andrew which struck Homestead Florida on August 24th 1992. Andrew is only the 3rd cat.-5 Hurricane to ever make landfall anywhere in the United States since records have been kept. The storm produced sustained winds of 165-MPH with gusts of 220-MPH in parts of South Miami-Dade County.

Quoting twincomanche:Worse yet those that demean people all the time and are generally mean spirited with everyone. I enjoy the back and forth of ideas but not people who enjoy putting people down and trying to demonstrate their superiority.

You know who said this?

"Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen."